1. Field of the Invention
This invention relates to a solid sensor provided with a charge accumulating portion which accumulates electric charges as a latent image charge in amounts depending upon the amounts of radiation to which parts thereof are exposed.
2. Description of the Related Art
There have been proposed various image information recording and read-out apparatuses in which a solid sensor which once accumulates in its charge accumulating portion electric charges corresponding to detected amounts of radiation representing a radiation image of an object as a latent image charge and outputs an electric signal representing the radiation image of the object on the basis of the latent image charge is employed. Among various types of solid sensors employed in such image information recording and read-out apparatuses, there have been known those of an optical read-out system in which the latent image charge is read out by projecting reading light (reading electromagnetic wave).
We have proposed an optical read-out solid sensor in which high-response read-out is compatible with high signal fetch efficiency, for instance, in U.S. Pat. No. 6,268,614, European Laid-open Nos. 1 041 400 and 1 041 401. The optical read-out solid sensor comprises a first conductive layer which is permeable to recording radiation or light excited by the recording radiation (will be referred to as xe2x80x9cthe recording lightxe2x80x9d, hereinbelow), a recording photoconductive layer which exhibits conductivity upon exposure to the recording light, a charge transfer layer which behaves like a substantially insulating material to an electric charge in the same polarity as that in which the first conductive layer is charged and behaves like a substantially conductive material to the electric charge in the polarity opposite to that in which the first conductive layer is charged, a reading photoconductive layer which exhibits conductivity upon exposure to reading light (reading electromagnetic wave) and a second conductive layer permeable to the reading light which are superposed one on another in this order, the signal charges (latent image charges) representing image information being accumulated in a charge accumulating portion formed in an interface between the recording photoconductive layer and the charge transfer layer.
In the solid sensor disclosed in European Laid-open Nos. 1 041 400 and 1 041 401, the electrode for the second conductive layer is in the form of a stripe electrode (a photo-charged pair generating electrode) comprising a plurality of linear electrodes each permeable to the reading light and a sub-stripe electrode (a photo-charged pair non-generating electrode) which is for outputting an electric signal whose level changes with the amount of latent image charge accumulated in the charge accumulating portion and comprises a plurality of linear electrodes is provided in the second conductive layer so that the linear electrodes of the stripe electrode and the linear electrodes of the sub-stripe electrode are alternately disposed in parallel to each other.
When a sub-stripe electrode comprising a plurality of linear electrodes is thus provided in the second conductive layer, another capacitor is formed between the charge accumulating portion and the sub-strip electrode, and it becomes feasible to give the sub-stripe electrode transfer charges of a polarity opposite to that of the latent image charge, accumulated in the charge accumulating portion by the recording light, by charge rearrangement upon reading, whereby the amount of transfer charge to be distributed to the capacitor, formed between the charge accumulating portion and the stripe electrode, through the reading photoconductive layer can be reduced as compared with when the sub-stripe electrode is not provided. As a result, the amount of signal charge to be taken out from the solid sensor can be increased, whereby the reading efficiency can be improved, and high-response read-out can be compatible with high signal fetch efficiency.
However, the solid sensor provided with such a stripe electrode and a sub-stripe electrode gives rise to a problem that when, for instance, a part of the linear electrodes of the stripe electrode is broken, it becomes impossible to read out signals from the part of the broken linear electrode in the area remoter from the image information recording and read-out apparatus than the broken part. When a part of the linear electrodes of the sub-stripe electrode is broken, it becomes impossible to accurately read out signals from the part of the broken linear electrode in the area nearer to the image information recording and read-out apparatus than the broken part.
In view of the foregoing observations and description, the primary object of the present invention is to provide a solid sensor provided with linear electrodes which allows all the accumulated charge to be read out even if a part of the linear electrodes is broken.
In accordance with a first aspect of the present invention, there is provided a solid sensor comprising a first conductive layer permeable to recording light, a recording photoconductive layer exhibiting conductivity upon exposure to the recording light, a charge accumulating portion which accumulates as a latent image charge electric charges in an amount corresponding to the amount of the recording light to which the recording photoconductive layer is exposed, a reading photoconductive layer exhibiting conductivity upon exposure to reading light, and a second conductive layer provided with a photo-charged pair generating electrode formed by a plurality of linear electrodes permeable to the reading light and a photo-charged pair non-generating electrode formed by a plurality of linear electrodes arranged alternately with the linear electrodes of the photo-charged pair generating electrode, which layers are superposed one on another in this order, the linear electrodes of the photo-charged pair generating electrode being connected to a read-out apparatus, which reads out the latent image charge, so that outputs of the linear electrodes of the photo-charged pair generating electrode forming one pixel are synthesized and detected by the read-out apparatus, wherein the improvement comprises that
the linear electrodes of the photo-charged pair generating electrode forming one pixel are provided with a bypass connection which, when apart of the linear electrodes is broken, allows outputs of the part of the broken linear electrode on the side of the broken part remote from the read-out apparatus to be detected by the read-out apparatus bypassing the broken part of the linear electrode.
In accordance with a second aspect of the present invention, there is provided a solid sensor comprising a first conductive layer permeable to recording light, a recording photoconductive layer exhibiting conductivity upon exposure to the recording light, a charge accumulating portion which accumulates as a latent image charge electric charges in an amount corresponding to the amount of the recording light to which the recording photoconductive layer is exposed, a reading photoconductive layer exhibiting conductivity upon exposure to reading light, and a second conductive layer provided with a photo-charged pair generating electrode formed by a plurality of linear electrodes permeable to the reading light and a photo-charged pair non-generating electrode formed by a plurality of linear electrodes arranged alternately with the linear electrodes of the photo-charged pair generating electrode, which layers are superposed one on another in this order, the linear electrodes of the photo-charged pair non-generating electrode being connected to a read-out apparatus, which reads out the latent image charge, so that outputs of the linear electrodes of the photo-charged pair non-generating electrode forming one pixel or a plurality of pixels are synthesized and detected by the read-out apparatus, wherein the improvement comprises that
the linear electrodes of the photo-charged pair non-generating electrode are provided with a bypass connection which, when a part of the linear electrodes is broken, allows outputs of the part of the broken linear electrode on the side of the broken part remote from the read-out apparatus to be detected by the read-out apparatus bypassing the broken part of the linear electrode.
The xe2x80x9csolid sensorxe2x80x9d of the present invention may be further provided with another or other layers and/or a micro conductive member (micro plate) so long as it comprises a first conductive layer, a recording photoconductive layer, a reading photoconductive layer and a second conductive layer superposed one on another in this order with a charge accumulating portion formed between the recording photoconductive layer and the reading photoconductive layer.
The charge accumulating portion may be formed in various ways. For example, the charge accumulating portion may be formed in an interface between a charge transfer layer and the recording photoconductive layer as disclosed in U.S. Pat. No. 6,268,615 and European Laid-open No. 1 041 400, may be formed in a trap layer or an interface between a trap layer and the recording photoconductive layer as disclosed, for instance, in U.S. Pat. No. 4,535,468, or may be formed by providing a micro conductive member which accumulates the latent image charges as disclosed in European Laid-open No. 1 041 401.
The xe2x80x9cphoto-charged pair generating electrode formed by a plurality of linear electrodes permeable to the reading lightxe2x80x9d means an electrode which allows the reading light to reach the reading photoconductive layer passing therethrough, thereby generating photo-charged pairs in the reading photoconductive layer. The xe2x80x9cphoto-charged pair non-generating electrodexe2x80x9d is an electrode for outputting an electric signal at a level depending on the amount of the latent image charge accumulated in the charge accumulating portion. Though it is preferred that the photo-charged pair non-generating electrode be impermeable to the reading light, it need not be impermeable to the reading light in the case where a light-shielding layer impermeable to the reading light is disposed between the photo-charged pair generating electrode and the reading light projecting means. The expression xe2x80x9cimpermeable to the reading lightxe2x80x9d should be broadly interpreted xe2x80x9csubstantially impermeable to the reading lightxe2x80x9d where though the reading light can slightly pass through the light-shielding layer or the photo-charged pair non-generating electrode, the amount of photo-charged pairs generated by the reading light passing therethrough is negligible. That is, the photo-charged pairs generated in the reading photoconductive layer may include to some extent those generated by small amount of reading light.
The reading light may be any light or radiation so long as it makes it feasible to transfer the electric charges through the solid sensor so that the latent image can be electrically read out.
xe2x80x9cThe linear electrodes of the photo-charged pair generating electrode forming one pixelxe2x80x9d or xe2x80x9cthe linear electrodes of the photo-charged pair non-generating electrode forming one pixel or a plurality of pixelsxe2x80x9d means linear electrodes which contribute to detection of signals representing one pixel or more pixels as seen in a direction perpendicular to the longitudinal direction of the linear electrodes.
In the solid sensor in accordance with the present invention, the photo-charged pair generating electrode and the photo-charged pair non-generating electrode of the second conductive layer are generally spaced from each other in the direction in which the layers are superposed and an insulating layer may be interposed between the photo-charged pair generating electrode and the photo-charged pair non-generating electrode of the second conductive layer.
The solid sensor of the present invention may be applied to the known recording method, the known reading method and the known image information recording and read-out apparatus such as disclosed in Japanese Unexamined Patent Publication No. 2000-284056 without modification of them.
In the solid sensor of the present invention, even if a part of the linear electrodes is broken, outputs of the part of the broken linear electrode on the side of the broken part remote from the read-out apparatus can be detected bypassing the broken part of the linear electrode by the read-out apparatus through the bypass connection, whereby adverse affect of breaking of the linear electrodes can be minimized.